Rear sag - towing

[Raven]

Apologies up front, since this has probably been addressed already, but I can't find the answers using the search function.
What is the best way to deal with rear sag when towing a 4,000 lb. trailer?
I do use a weight distributing hitch.
I am thinking Airlift 1000's in the rear springs would be the simplest and least expensive.
Do you think heavier springs would be a better way to go?
Spacers? - other suggestions?

The air bags would also allow me to drop the pressure for day to day driving, and boost them for towing. - make sense?

 

[cacarbuff]

If you have significant sag, I don't think you have your wdh set up properly. If you give us the details of your truck and hitch setup, maybe we can help. For comparisons sake, I drive an '05 v8 with a properly set up 10k lb wdh and tow a 5-7k lb trailer with a 600-850 lb tongue weight. With my HD metal tech lt coils I sag about an inch and a half.

 

[riceandpho]

Firestone coil rite is a lot easier to install, since all the fittings is compression, just push in the newly cut end to the connectors and make sure it's tight, watch the YouTube video on the 4runner install, etrailer.com have it posted too.

 

[ebg18t]

Doesn't sound like your WDH is setup properly.

When my WDH is not used the rear of my truck settles about 2.5" under the weight of our travel trailer. With the WDH the rear of my truck settles about 0.5".

When I first set my WDH up for the first time it took close to 2hrs before I got the proper ball height and the right # of links on the chain. I find a lot of people don't get the height setup properly in the beginning. I use the BlueOx SwayPro.

If you need too, adding airbags is an option. But start with real evaluating the WDH setup. If you want help post your WDH model and maybe we can help with the setup.

 

[Raven]

Hey Guys, thanks for the thoughtful input! To keep my post from getting too long, I obviously left out some key information you would need to answer my noobie question.
1. I don't even have my Runner yet! (soon). I am currently using an Anderson WDH with built-in sway control, on my 2007 FJ. I have indeed learned how to adjust it properly for a level ride, and it seems to work very well.

2. I understand the basic principles involved with the WDH, but it does put considerable stress on the hitch and related components. Think about it - you are using a downward force on the ball to "pick up" the back end of the car, wheelbarrow style, and transfer weight to the front end.

3. My thinking is, if I raise the back end with HD springs or air bags first, then the WDH has less work to do - it's main job will be sway control, and I can set it up with less tension on the chains. Springs, air bags and WDH will share the load.

4. The air bags will also be available then for when I am carrying a heavy load in the back of the Runner.

5. It appears from posts in this forum, that the 4Runner has more of a rear sag problem than the FJ, and quite a few people have added heavier springs, spacers, coil-overs or air bags as a remedy. I am just getting proactive, so that when my Runner arrives in my driveway, I have all my ducks in a row.
I guess I should drive it for a bit first to see if I have a problem.

 

[Titanpat57]

If you're talking a #4000 trailer...you're looking at 400 -500# in tongue weight.

Its not if you will have a problem...I would say plan on it. LT tires will also add in better performance.

 

[ebg18t]

Hey Guys, thanks for the thoughtful input! To keep my post from getting too long, I obviously left out some key information you would need to answer my noobie question.
1. I don't even have my Runner yet! (soon). I am currently using an Anderson WDH with built-in sway control, on my 2007 FJ. I have indeed learned how to adjust it properly for a level ride, and it seems to work very well.

2. I understand the basic principles involved with the WDH, but it does put considerable stress on the hitch and related components. Think about it - you are using a downward force on the ball to "pick up" the back end of the car, wheelbarrow style, and transfer weight to the front end.

3. My thinking is, if I raise the back end with HD springs or air bags first, then the WDH has less work to do - it's main job will be sway control, and I can set it up with less tension on the chains. Springs, air bags and WDH will share the load.

4. The air bags will also be available then for when I am carrying a heavy load in the back of the Runner.

5. It appears from posts in this forum, that the 4Runner has more of a rear sag problem than the FJ, and quite a few people have added heavier springs, spacers, coil-overs or air bags as a remedy. I am just getting proactive, so that when my Runner arrives in my driveway, I have all my ducks in a row.
I guess I should drive it for a bit first to see if I have a problem.

The Anderson WDH is awesome! Keep in mind that the chain tension you use for shifting load forward also controls the sway. I wouldn't worry about the tension or pressure it puts on the frame. If you bump up your rear springs to the OME 895 (mediums) your future 4Runner will tow well with that WDH system. You may see some 4Runners will saggy butts since the hitch (ball point ) is farther back than the FJ. Make sure your future 4Runner has the upgraded frame mounted hitch. The 4Runner does seem to tow better than the FJ due to the longer wheelbase. If you go the airbag road, they are only $100.

 

[Raven]

If you bump up your rear springs to the OME 895 (mediums) your future 4Runner will tow well with that WDH system. Make sure your future 4Runner has the upgraded frame mounted hitch.

Thanks ebg: - So, it is your opinion that upgraded springs would be better than airbags?

Are you suggesting an after-market frame mounted hitch? Since the Runner comes with a good hitch bolted to the x- member, and that cross member is strongly welded to the frame rails, I am not sure I can see the difference?
I believe I read somewhere that Toyota claims their cross member is easily capable of handling the strain of a weight distributing hitch.

 

[riceandpho]

i use airbags since i have a constant 400lb load in my cargo, i think if you just did springs you still get sag right after a while, the airbags firmed up the back, so i dont hit the bumpstops(harsh ride), im at 16-18 psi for my bags and it seems to ride like a new truck. if you do air bags(100 bucks) i suggest you to also install a tee fitting, itll keep both bags at the same shared psi. i bought my kit at sdtrucksprings.com

 

[ebg18t]

Thanks ebg: - So, it is your opinion that upgraded springs would be better than airbags?

Are you suggesting an after-market frame mounted hitch? Since the Runner comes with a good hitch bolted to the x- member, and that cross member is strongly welded to the frame rails, I am not sure I can see the difference?
I believe I read somewhere that Toyota claims their cross member is easily capable of handling the strain of a weight distributing hitch.

Just made sure the hitch is good. The v8 has the heavier hitch(frame mounted), the v6 has a weaker hitch (crossmember mounted).

Before doing anything drive the truck and see if you want new/fresh suspension. Many of us upgrade since the oem suspension is so soft, plus we wanted lift. What suspension did you do on your FJ?

 

[Raven]

I agree - driving it for a while before making any decisions re: mods makes a lot of sense.
ps., the FJ is stock. I was considering air bags for it, but then decided to go 4Runner instead.

 

[riceandpho]

Did you know the 4runner and fj uses the same airbags from firestone and airlift.

 

[Raven]

Did you know the 4runner and fj uses the same airbags from firestone and airlift.

Yes, I was aware of that, thanks!
On that topic (as OP, am I allowed to be responsible for "thread drift"? LOL),
any opinions on which is better for the 4Runner, Firestone CoilRite, or Airlift 100's?

 

[ebg18t]

Yes, I was aware of that, thanks!

On that topic (as OP, am I allowed to be responsible for "thread drift"? LOL),

any opinions on which is better for the 4Runner, Firestone CoilRite, or Airlift 100's?

All are about the same. I used firestone on my old truck, but many have used the airlift.

 

[riceandpho]

i like my firestone coilrite, airlift use clamps on there connections , vs firestone use compression type. where you able to watch the install video on etrailers.com? they use the firestone on the 5th gen install and its the same procedure to install on the 4th gen, get a tee fitting so you dont have one bag with more pressure than the other.

 

[Raven]

Yes, if I go with airbags (and I am leaning that way), I will have one feed for both bags, using a "T"
I am considering a built-in on-board air compressor.